JP2011060850A - Cu-BASED WIRING MATERIAL PRECURSOR, Cu-BASED WIRING MATERIAL, AND FORMING METHOD THEREFOR - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a Ti-based self diffusion barrier film on a wiring surface, even if a Cu-Ti-based sputter film is heat-treated at a temperature lower than the conventional temperatures. <P>SOLUTION: After forming an extremely thin Ti-based film on a base material 1 as a first film 2, by having a compound film including a slope structure of a Ti-based material of a Ti-based material and a Cu-based material formed as a second film 3, and a third film 4 formed on the compound film as a Cu-based electrode, a precursor having a three-layer structure is formed. By heat-treating the precursor at 450C° or lower, the Cu-based electrode including the Ti-based barrier film can be formed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to, for example, a long wiring used for FPD (for example, a liquid crystal panel (LCD)), a copper alloy used as a low resistance wiring used in a narrow range of LSI, a Cu alloy wiring, and The present invention relates to a method of forming a Cu alloy wiring.

Conventionally, Al and Al alloys have been used as wiring materials for FPDs (flat panel displays) and semiconductor elements, but there is no delay in signal response as wiring becomes longer or finer, or wiring Cu and Cu alloys, which have low resistance, have come to be used as wiring materials so that the wiring resistance does not increase due to the miniaturization of the cross-sectional area.
Although Cu is a low resistance, it is a very active metal, so it can easily diffuse into Si and SiO ₂ and cause Cu contamination problems. Cu also has problems such as low adhesion to the substrate and electromigration, so after forming a barrier film such as TiN or TaN between Cu and the substrate, Cu or Cu alloy A method of forming a wiring film is generally used (see, for example, Patent Document 1).

Recently, since the electrode portion is reduced by the thickness of the barrier film, the barrier layer has influenced the resistance value of the electrode as the LSI becomes narrower. Therefore, research to make the barrier layer extremely thin has been made, and the alloy component that diffuses to the surface and becomes the barrier film during the heat treatment step after the Cu film is formed is added to Cu beforehand. Studies have been made that the barrier film need not be formed (hereinafter, the barrier film formed in this manner is referred to as a self-diffusion barrier film, if necessary). For example, Patent Document 2 describes a Cu-Mn alloy system and describes that a self-diffusion barrier film of Mn oxide or CuMn composite oxide is formed at the interface with an adjacent substance by heat treatment. Further, Patent Document 3 describes a Cu—Ge alloy system, which also describes that a Ge oxide is formed on the surface of the alloy film and functions as a self-diffusion barrier film.
However, self-diffusion barrier films in these material systems have not yet been put into practical use in terms of reliability of the barrier function. Therefore, many companies continue to adopt a method of forming a Cu film after forming a Ti-based barrier film in advance.

  Regarding Ti-based self-diffusion barrier films, heat treatment is also being studied after film formation with Cu-Ti alloy. In Non-Patent Document 1, when a sputtered film of Cu—Ti alloy is heat-treated at 400 ° C., it is found that Ti diffuses to the surface, suggesting the possibility of realizing a self-diffusion barrier film by this technology. This Ti film could not be a perfect barrier film. Since a high temperature of 800 ° C. is necessary to diffuse Ti into a barrier film (see, for example, Patent Document 4), it can be applied to a gate electrode formed on a substrate for LCDs, but after forming a semiconductor element It is difficult to apply to the source / drain electrodes used, and it cannot be applied to LSI.

JP-A 63-156341 International Publication No. 2006/025347 Pamphlet JP 2005-191363 A Japanese Patent Laid-Open No. 3-196619

Journal of Electronic Materials, Vol34, No.5,2005, p592-599

If a Ti-based self-diffusion barrier film can be formed at about the heat treatment temperature used in the LCD manufacturing process, LSI manufacturing process, etc., a reliable Ti-based barrier film can be made extremely thin to form a Cu-based wiring. Since it can be formed between the substrate and the substrate, it can sufficiently cope with narrowing of the wiring of the LSI.
Therefore, the present invention provides a Cu-based wiring material precursor and a Cu-based wiring material that can form a Ti-based self-diffusion barrier film on the wiring surface even if the Cu-Ti-based sputtered film is heat-treated at a lower temperature than before. And it aims at providing these manufacturing methods.

In order to solve the above problems, the present inventors have created the following means.
(1) A Cu-based wiring material precursor composed of a first film, a second film, and a third film, wherein the first film is Ti or Ti compound formed on a substrate The second film is a composite film of Ti or Ti compound formed on the first film and Cu or Cu alloy, and an interface in contact with the first film The composition ratio of Ti or Ti compound and Cu or Cu alloy gradually changes in the film thickness direction between the film surface and the composition of Ti or Ti compound between the interface contacting the first film and the film surface The ratio is gradually reduced from 1 to 0 and the composition ratio of Cu or Cu alloy is gradually increased from 0 to 1, and the third film is formed only from Cu or Cu alloy formed on the second film. A Cu-based wiring material precursor characterized by being a film.
(2) A Cu-based wiring material precursor comprising a first film, a second film, and a third film, wherein the first film is Ti or a Ti compound formed on a substrate The second film is a film laminated on the first film, and is a film of 2n layers, where n is a positive integer, and k is from 1 to n. As an integer, the 2k-1st layer from the first film side is a layer made of Ti or a Ti compound, and its layer thickness is maximum when k is 1, and converges to 0 as k approaches n. The 2k-th layer from the first film side is a layer made of Cu or Cu alloy, and the layer thickness is maximum when k is n and converges to 0 as k approaches 1, The Cu-based wiring material precursor is characterized in that the film is a film made of only Cu or Cu alloy formed on the second film.
(3) The Cu-based wiring material precursor according to (1) or (2), wherein the thickness of the first film is 1 nm to 10 nm.
(4) The Cu-based wiring material precursor according to any one of (1) to (3), wherein the thickness of the second film is 10 nm to 50 nm.
(5) Cu comprising a first film formed on a substrate, a second film formed on the first film, and a third film formed on the second film A wiring material, wherein the first film is a Ti-based barrier film and is a film made of only Ti or a Ti compound, and the second film is a composite film of Ti-based and Cu-based, The composition ratio of Ti or Ti compound and Cu or Cu alloy gradually changes in the film thickness direction between the interface in contact with the first film and the film surface, and the interface in contact with the first film to the film surface The composition ratio of Ti or Ti compound gradually decreases from 1 to 0, and the composition ratio of Cu or Cu alloy gradually increases from 0 to 1, and the third film is a Cu-based film, A Cu-based wiring material characterized in that it is a film made of only Cu or Cu alloy.
(6) Between the base material and the Cu-based film formed by heat-treating the Cu-based wiring material precursor according to any one of (1) to (4), a Ti-based barrier film, A Cu-based wiring material having a composite film of Ti and Cu.
(7) First by a method of forming a film using a Cu or Cu alloy target and a Ti or Ti compound target using a PVD apparatus capable of simultaneously controlling and sputtering a plurality of targets. A method for forming a Cu-based wiring material precursor comprising a film, a second film, and a third film, wherein a Ti or Ti compound target is used as the first film on the substrate. A step of laminating only Ti or Ti compound, a step of laminating the second film on the first film using a Cu or Cu alloy target and a Ti or Ti compound target, and Cu or Cu. In the step of laminating only the Cu or Cu alloy on the second film as the third film using an alloy target, and in the step of laminating the second film, Ti or Ti Compound target and Cu or Cu alloy The sputtering power applied to the Ti or Ti compound target is gradually reduced from the power value when forming the first film to 0 and applied to the Cu or Cu alloy target so that the target is simultaneously fired. A method of forming a Cu-based wiring material precursor, wherein the second film is formed by gradually increasing a sputtering power to be generated from 0 to a power for forming the third film.
(8) A first method by which a film is formed using a Cu or Cu alloy target and a Ti or Ti compound target using a PVD apparatus capable of simultaneously controlling and sputtering a plurality of targets. A method for forming a Cu-based wiring material precursor comprising a film, a second film, and a third film, wherein a Ti or Ti compound target is used as the first film on the substrate. A step of laminating only Ti or Ti compound, a step of laminating the second film on the first film using a Cu or Cu alloy target and a Ti or Ti compound target, and Cu or Cu. And stacking only Cu or a Cu alloy on the second film as the third film using an alloy target, and in the step of stacking the second film, Ti or Ti compound target as an integer And 2n layer films are alternately used with Cu or Cu alloy target, and k is an integer from 1 to n, and is composed of 2k-1st Ti or Ti compound from the first film side. The layer is formed by gradually shortening the firing interval of the Ti or Ti compound target so that the maximum is when k is 1 and converges to 0 as k approaches n, and 2 k from the first film side. The second Cu or Cu alloy layer should be formed so that the firing interval of the Cu or Cu alloy target is gradually increased, and the maximum when k is n and converges to 0 as k approaches 1. A method of forming a Cu-based wiring material precursor characterized by the following.
(9) The method for forming a Cu-based wiring material precursor according to (7) or (8), wherein the thickness of the first film is 1 nm to 10 nm.
(10) The method for forming a Cu-based wiring material precursor according to any one of (7) to (9), wherein the thickness of the second film is 10 nm to 50 nm.
(11) Cu or Cu alloy wiring material precursor formed by the method for forming a Cu-based wiring material precursor according to any one of (7) to (10) is heat-treated, and a base material, a Cu-based film, A Cu-based wiring material forming method comprising forming a Cu- or Cu-alloy wiring material having a Ti-based barrier film therebetween.
(12) The method for forming a Cu-based wiring material according to (11), wherein the heat treatment temperature is 450 ° C. or less.

  According to the present invention, Ti-based self-diffusion with a sufficiently low barrier property even at an ultra-thin temperature at a lower heat treatment temperature than before (for example, about the heat treatment temperature performed in the LCD manufacturing process or LSI manufacturing process). A barrier film can be formed between the Cu-based wiring and the base material.

It is the figure which showed typically the cross section of the Cu type | system | group wiring material precursor by this embodiment. It is the figure which showed the time passage of opening and closing of the separate shutter which covers a Ti target and Cu target at the time of forming the Cu type wiring material precursor by Example 1-1. It is the figure which showed time passage of opening and closing of the separate shutter which covers a Ti target and Cu target at the time of forming Cu system wiring material precursor by Example 1-2. It is the figure which showed the time passage of opening and closing of the separate shutter which covers a Ti target and Cu target at the time of forming the Cu-type wiring material precursor by the comparative example 1-1.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the Cu wiring material of the present embodiment, for example, a precursor as shown in FIG. 1, that is, a Ti film (first film 2) made of only Ti exists at the interface with the substrate 1, and immediately above it The Ti content decreases as the composite film of Ti and Cu with a relatively large Ti content or the laminated film of the Ti film and Cu film (second film 3) moves to the surface side. It is obtained by heat-treating a precursor having a structure in which a Cu film (third film 4) made of only Cu is formed on the surface of the wiring material.
In FIG. 1, although described as Ti and Cu, Ti may be a Ti compound, for example, TiN, and Cu may be a Cu alloy. It is possible to apply a TiN film if sputtering is performed from a Ti target in a nitrogen gas mixed atmosphere first, and a TiO ₂ film can be applied if sputtering is performed from a Ti target in an oxygen gas mixed atmosphere. . If an alloy target such as Cu-Mn is used instead of the Cu target, a Cu alloy such as Cu-Mn can be formed. Hereinafter, Ti, TiN, and the like are referred to as Ti-based, and Cu, Cu-Mn, and the like are referred to as Cu-based.

To form the precursor, Ti or a Ti compound is first formed on the surface of the substrate 1 as the first film 2. This serves as a barrier film and also has an effect as a base layer that compensates for poor adhesion between the Cu or Cu alloy film and the substrate 1. When forming a film of Ti or Ti compound alone for use as a barrier film, it is common to form Ti or Ti compound with a thickness of several tens to hundreds of nm by a method such as sputtering or CVD. It is. However, in the case of the precursor of the present embodiment, since Ti or Ti compound is also supplied from the gradient composition part in the second film 3, the film of Ti or Ti compound can be made thinner, For example, it may be 1 nm to 10 nm.
Ti or Ti compound films can be obtained by forming Ti films obtained in an inert atmosphere or in a vacuum, TiN films obtained by forming films in a nitrogen mixed atmosphere, and forming films in an oxygen mixed atmosphere. TiO ₂ film to be, TiC film obtained by film formation in an atmosphere containing carbon sources TMS etc., and the like. Either of these functions as a barrier film that prevents Cu or Cu alloy from diffusing, and also has the effect of improving the adhesion between the Cu or Cu alloy film and the substrate.

The second film 3 of the precursor is a composite film of Ti or Ti compound and Cu or Cu alloy, and Ti or Ti toward the far side from the first film made of Ti or Ti compound. It has a graded composition in which the Ti compound content decreases gradually.
In order to form a graded composition, a multi-physical physical vapor deposition (PVD) apparatus having at least two targets is used, Ti or Ti compound is arranged on one target, Cu or Cu alloy is arranged on the other target, A gradient composition can be formed by controlling the amount of each target used. First, increase the amount of Ti or Ti compound target used, and gradually increase the amount of Cu or Cu alloy target used. The usage amount of the target can be changed by controlling the power applied to the target and the application time. There are two methods for forming the gradient composition.

The first method is to ignite a Ti or Ti compound target and a Cu or Cu alloy target at the same time so that the sputtering power applied to the Ti or Ti compound target is the power value when forming a Ti-based film. In this method, the sputtering power applied to the Cu or Cu alloy target is gradually increased from 0 to the power for forming a Cu-based film.
In the second method, n is a positive integer, and a Ti or Ti compound target and a Cu or Cu alloy target are alternately used in this order to stack 2n layers. At this time, assuming that k is an integer from 1 to n, the Ti or Ti compound target is ignited for the 2k-1 layer (2k-1st from the first layer 2 side) of Ti or Ti compound. The interval is gradually shortened so that the firing interval is maximum when k is 1, and the firing interval converges to 0 as k approaches n. The second k layer (the first layer 2 side) For the layer made of Cu or Cu alloy 2), the firing interval of the Cu or Cu alloy target is gradually increased, and the firing interval when k is n is the maximum, and as k approaches 1 In this method, the firing interval is converged to zero.

The atmosphere during the formation of the second film 3 is preferably an inert gas atmosphere or a vacuum. This is because Cu or Cu alloy may also react in an oxygen-containing atmosphere or an atmosphere containing a carbon source such as TMS, and Cu or Ti compounds and Cu components are concentrated by heat treatment. This is to prevent the concentration of components. In particular, film formation in an Ar atmosphere is preferable because it does not react with Cu or a Cu alloy and is economical.
The thickness of the second film 3 is preferably about 10 nm to 50 nm. When the thickness of the second film 3 is less than 10 nm, the supply of Ti or Ti compound becomes insufficient, and the characteristics as a barrier film are deteriorated. When the thickness of the second film 3 is more than 50 nm, the Ti or Ti compound is deteriorated. Although it is sufficiently supplied, it takes time for the heat treatment to sufficiently concentrate Ti or the Ti compound. Further, the thickness of Ti or Ti compound is more preferably 10 nm to 30 nm. If the thickness of Ti or Ti compound is more than 30 nm, sufficient characteristics as an intermediate layer can be obtained, but the film formation time becomes longer and the target is consumed, which is economically disadvantageous.

The second film 3 may be adjusted so that the ratio of Ti or Ti compound in this thickness decreases from the first film 2 side toward the third film 4 side. If Ti or Ti compound of 50% or more of all Ti or Ti compound in the second film 3 is contained up to 50% of the thickness from one film 2 side, sufficient Ti or Ti compound Was found to diffuse into the first film 2. That is, on the first film 2 side, Ti or Ti compound is simply reduced to half the thickness of the second film 3, or on the first film 2 side, the thickness of the second film 3 is half. However, the ratio of Ti or Ti compound may be reduced so that more Ti or Ti compound is contained than in the case of simple reduction.
However, it is not always necessary to do this, and the second film 3 has a Ti or Ti compound ratio that decreases from the first film 2 side toward the third film 4 side. good. For example, the composition ratio of Ti or Ti compound gradually decreases from 1 (100%) to 0 and the composition ratio of Cu or Cu alloy decreases from 0 to 1 (100%) from the interface in contact with the first film 2 toward the film surface. The second film 3 can be formed so as to increase gradually.

The third film 4 of the precursor is a single layer film of Cu or Cu alloy, and is a layer that plays a role as an original electrode. For the third film 4, after forming the second film 3 and stopping the film formation of Ti or Ti compound, a single layer film of Cu or Cu alloy may be formed as it is to a required thickness. The thickness of the third film 4 is the required electrode thickness, and is often, for example, 200 nm to 500 nm. Of course, if a thick electrode is required in the design, a film with a thickness of several μm may be formed. If the electrode is used at a fine interval of about 100 nm, the thickness of the third film 4 is adjusted to that thickness. It ’s fine.
The precursor is formed by sequentially stacking the above three films.
By applying heat treatment to the precursor thus obtained, Ti or Ti compound is concentrated on the interface side with the substrate 1 (substrate), and the inside of the electrode is only Cu or Cu alloy, and wiring It is possible to realize a low resistance.
The precursor should preferably be heat treated in a vacuum or inert atmosphere. This is because Cu or Cu alloy concentrates Cu or Cu component inside without causing reaction such as oxidation.

  The heat treatment temperature depends on the thickness of the precursor, but is preferably 450 ° C. or lower. In the case of the conventional self-diffusion method using a Cu-Ti alloy, a heat treatment at 650 ° C. was necessary to sufficiently diffuse Ti or a Ti compound to the interface with the base material. By limiting the diffusion region of Ti or Ti compound by the gradient composition, Ti or Ti compound can be sufficiently diffused to the interface with the substrate 1 by heat treatment at 450 ° C. When most of the Ti or Ti compound is prepared near the first film 2 side of the second film 3 of the precursor, the heat treatment temperature can be further lowered, and even when heat treatment at 350 ° C., Ti or Ti It was possible to diffuse the compound to the interface with the substrate 1. When the heat treatment temperature is lower than 350 ° C., it takes too much time to cause diffusion of Ti or Ti compound. Further, even if the heat treatment temperature is higher than 450 ° C., Ti or Ti compound can be diffused, but the semiconductor layer and the like are damaged, so the heat treatment temperature is preferably 450 ° C. or lower. Therefore, heat treatment at 350 ° C. to 450 ° C. is more preferable.

  The heat treatment time can be appropriately adjusted within a range in which Ti or a Ti compound can be diffused to the interface with the substrate 1 and the function as a barrier film can be secured. Moreover, the heat pattern of heat processing can be suitably adjusted similarly to heat processing time. For example, depending on the temperature rising time until the temperature range (350 ° C. to 450 ° C.) described above is reached, the holding time may be 0 hours because Ti or Ti compound diffuses without holding time (ie, for example, The temperature may be lowered immediately after the temperature has been raised to the specified temperature range). Further, the holding time when the heat treatment is performed with the heat pattern holding the temperature in the above-described temperature range is preferably 6 hours or less. This is because even if heat treatment is performed for a long time, the amount of diffusion does not change so much, and the productivity is deteriorated due to the time required for the process. Furthermore, from the viewpoint of diffusing Ti or a Ti compound to the interface with the base material 1 and ensuring the function as a barrier film by heat treatment as short as possible, the heat treatment is performed at a temperature in the temperature range described above. The holding time is more preferably 1 to 3 hours (for example, about 2 hours).

In the Cu wiring material thus formed, the thickness of the first film 2 after the heat treatment is preferably 1 nm to 15 nm, and the thickness of the second film 3 after the heat treatment is preferably 1 nm to 7 nm. That is, the thickness of the film containing Ti after the heat treatment is preferably 2 nm to 22 nm. As described above, the thickness of the first film 2 in the precursor may be, for example, 1 nm to 10 nm. Similarly, the thickness of the second film 3 in the precursor is preferably about 10 nm to 50 nm. This is because, within such a range, it can be evaluated that Ti is sufficiently concentrated by heat treatment.
By doing the above, a Ti-based self-diffusion barrier film that is extremely thin and sufficiently excellent in barrier properties at the temperature of the heat treatment performed in the LCD manufacturing process or LSI manufacturing process can be formed with Cu-based wiring and substrate. Between the two.

  It should be noted that the embodiments of the present invention described above are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. Is. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

Examples of the present invention will be described below. However, the present invention is not limited to the examples.
Example 1
A Cu target and a Ti target were respectively installed using a binary target type DC magnetron sputtering apparatus (SPF-430 manufactured by Canon Anelva). In this sputtering apparatus, an individual shutter for individually blocking the sputtering is provided on each target, and it is the same as controlling the firing interval while continuing to fire two targets by the opening and closing time of this individual shutter. It is a sputtering apparatus that can obtain the effect. Using this sputtering apparatus, a precursor composed of three layers of films was formed on an alkali-free glass substrate.
Thereafter, heat treatment was performed at a predetermined temperature in a vacuum heat treatment apparatus (RI-1500MH manufactured by Tokyo Vacuum Co., Ltd.) to form a Cu electrode film. Using electron microscopic observation and EDS (energy dispersive X-ray spectroscopy) analysis of the cross section of the precursor and the heat-treated Cu electrode, the thickness of each film of the precursor (the thickness of the layer in which only Ti exists, Ti and Cu) And the thickness of the layer containing only Cu, and the thickness of the layer containing Ti after heat treatment was determined using EDS analysis of electron microscope.

(Example 1-1)
Alkali-free glass was placed in a dual target DC magnetron sputtering system, and only a Ti target was used in a nitrogen atmosphere of 0.13 Pa, and a film was formed for 30 seconds with an applied power of 300 W. As a precursor first film 2 Ti-N (a mixed film of TiN and Ti ₂ N) having a thickness of 10 nm was formed.
Next, the Ti target and the Cu target were ignited with an applied power of 300 W in an Ar atmosphere of 0.13 Pa, and the Ti target shutter and the Cu target shutter were opened and closed for 2 minutes as shown in FIG. The second film 3 of the precursor having a gradient composition of / Cu is formed, and then the Ti target is stopped and the Cu target is continuously ignited, and the precursor is deposited for 15 minutes at an applied power of 300 W. The third film 4 was formed.
The thickness of the first film 2 was 10 nm, the thickness of the second film 3 was 20 nm, and the thickness of the third film 4 was 200 nm. Note that about 70% of the Ti in the second film 3 was concentrated closer to the first film 2.
Using this precursor-attached glass substrate as the base material 1, heat treatment is performed at 450 ° C. for 2 hours in a vacuum heat treatment apparatus (vacuum furnace) to obtain a Cu electrode film in which Ti is concentrated at the interface between the glass substrate and the Cu film. I was able to.
The thickness of the layer containing Ti was 18 nm, and before the heat treatment, it was 30 nm (= the thickness of the first film 2 10 nm + the thickness of the second film 3 20 nm). It shows that Ti diffused and concentrated toward 2. In addition, in the Cu electrode film, Ti is not present in a portion near the third film 4 of the second film 3 as a precursor, and only a Cu film is formed. 4 was found to be absorbed. The thickness of the layer containing only Ti or Ti compound was 14 nm within the detection error range.

(Example 1-2)
Compared to Example 1-1, only the shutter opening and closing time during the formation of the second film 3 was changed as shown in FIG. 3 to form a precursor. The thickness of the first film 2 is 10 nm, the thickness of the second film 3 is 18 nm, the thickness of the third film 4 is 200 nm, and about 80% of Ti in the second film 3 is the first film 2. It was thickening.
In the same manner as in Example 1-1, heat treatment was performed using a vacuum heat treatment apparatus (vacuum furnace). The thickness of the layer containing Ti was 13 nm. Since the thickness of the layer containing Ti before heat treatment was 28 nm (= first film thickness 10 nm + second film thickness 18 nm), the Ti-enriched region of the second film 3 is the first film 2. This suggests that he was approaching quite close. In addition, in the Cu electrode film, Ti is not present in a portion near the third film 4 of the second film 3 as a precursor, and only a Cu film is formed. 4 was found to be absorbed. The thickness of the layer containing only Ti or Ti compound was 12 nm within the detection error range.

(Comparative Example 1-1)
Compared to Example 1-1, only the shutter opening and closing time during the formation of the second film 3 was changed as shown in FIG. 4 to form a precursor. The first film 2 has a thickness of 10 nm, the second film 3 has a thickness of 20 nm, and the third film 4 has a thickness of 200 nm. In the second film 3, more than 50% of Ti is concentrated closer to the third film 4. It was.
In the same manner as in Example 1-1, heat treatment was performed using a vacuum heat treatment apparatus (vacuum furnace). The thickness of the layer containing Ti was 25 nm. That is, the thickness of the layer containing Ti before heat treatment was 30 nm (= the thickness of the first film 2 10 nm + the thickness of the second film 3 20 nm). The total thickness of the first film 2 and the second film 3 is not much different, suggesting that the concentration of Ti is insufficient. Further, since Cu has entered near the first film 2, the function of Cu as a barrier film becomes insufficient, and this film is unsuitable.

(Example 1-3)
A precursor was formed in the same manner as in Example 1-1, and the heat treatment condition was 350 ° C. for 2 hours.
The thickness of the layer containing Ti was 20 nm. Since the thickness of the Ti-containing layer before the heat treatment was 30 nm (= 10 nm of the first film 2 +20 nm of the second film 3), the second film 3 was directed to the first film 2. This suggests that Ti diffused and concentrated. Further, in the Cu electrode film, Ti is not present in a portion near the third film 4 of the second film 3 as a precursor, and only the Cu film is formed, and this portion is the third film 4. It was found that it was absorbed. The thickness of the layer containing only Ti or Ti compound was 13 nm within the detection error range.

(Comparative Example 1-2)
A precursor was formed in the same manner as in Example 1-1, and the heat treatment conditions were 330 ° C. for 2 hours.
The thickness of the layer containing Ti was 25 nm. That is, the thickness of the layer containing Ti was not changed from the total thickness of the first film 2 and the second film 3 of the precursor, suggesting that the concentration of Ti was insufficient. Since Cu had penetrated close to the first film, the function of Cu as a barrier film became insufficient, and this film was unsuitable.

(Example 2)
A Cu target and a Ti target were respectively installed using a binary target type DC magnetron sputtering apparatus (SPF-430 manufactured by Canon Anelva). This sputtering apparatus is a sputtering apparatus capable of individually controlling the applied power applied to two targets, and capable of controlling the component ratio in the film according to the applied power when simultaneously ignited. .
A precursor was formed using this sputtering apparatus. First, non-alkali glass as a base material 1 was placed in a dual target type DC magnetron sputtering apparatus, and a film was formed for 1 minute at an applied power of 300 W using only a Ti target in a nitrogen atmosphere of 0.13 Pa. A 20 nm Ti—N film (a mixed film of TiN and Ti ₂ N) was formed as the first film 2.
Next, in an Ar atmosphere of 0.13 Pa, the Ti target was ignited with an applied power of 300 W, the applied power was reduced by 10 W every 4 seconds, the applied power was set to 0 W after 2 minutes, and the applied power for the Cu target. Is set to 0 W, and then fired to increase the applied power by 10 W every 4 seconds to form the second film 3 of the precursor having a Ti / Cu gradient composition, and 300 W is applied after 2 minutes. In the state where only the Cu target was ignited with electric power, the film was further formed for 15 minutes in this state, and the third film 4 of the precursor was formed.
The thickness of the first film 2 was 10 nm, the thickness of the second film 3 was 18 nm, and the thickness of the third film 4 was 200 nm. Note that about 80% of Ti in the second film 3 was concentrated closer to the first film 2.
The glass substrate with the precursor was heat-treated at 450 ° C. for 2 hours with a vacuum heat treatment apparatus (vacuum furnace), and a Cu electrode film in which Ti was concentrated at the interface between the glass substrate and the Cu film could be obtained.
The thickness of the layer containing Ti was 17 nm, and was 28 nm (= the thickness of the first film 2 +10 nm + the thickness of the second film 3) before the heat treatment. It shows that Ti diffused and concentrated toward 2. Further, in the Cu electrode film, the portion near the third film 4 of the second film 3 at the time of the precursor does not have Ti, and only the Cu film is formed. It was found that it was absorbed. The thickness of the layer containing only Ti or Ti compound was 13 nm within the detection error range.

DESCRIPTION OF SYMBOLS 1 Base material 2 1st film | membrane 3 2nd film | membrane 4 3rd film | membrane

Claims (12)

A Cu-based wiring material precursor comprising a first film, a second film, and a third film,
The first film is a film made of only Ti or Ti compound formed on a substrate,
The second film is a composite film of Ti or a Ti compound formed on the first film and Cu or a Cu alloy, and Ti is formed between an interface in contact with the first film and the film surface. Alternatively, the composition ratio of Ti compound and Cu or Cu alloy gradually changes in the film thickness direction, and the composition ratio of Ti or Ti compound gradually decreases from 1 to 0 between the interface contacting the first film and the film surface. And the composition ratio of Cu or Cu alloy gradually increases from 0 to 1,
The third film is a film made of only Cu or Cu alloy formed on the second film.
Cu-based wiring material precursor characterized by that. A Cu-based wiring material precursor comprising a first film, a second film, and a third film,
The first film is a film made of only Ti or Ti compound formed on a substrate,
The second film is a film laminated on the first film, wherein n is a positive integer and is composed of 2n layers, and k is an integer from 1 to n.
The 2k-1st layer from the first film side is a layer made of Ti or a Ti compound, and the layer thickness is maximum when k is 1, and converges to 0 as k approaches n,
The 2k-th layer from the first film side is a layer made of Cu or Cu alloy, and the layer thickness is maximum when k is n, and converges to 0 as k approaches 1,
The third film is a film made of only Cu or Cu alloy formed on the second film.
Cu-based wiring material precursor characterized by that.   The Cu-based wiring material precursor according to claim 1, wherein the first film has a thickness of 1 nm to 10 nm.   The Cu-based wiring material precursor according to any one of claims 1 to 3, wherein the thickness of the second film is 10 nm to 50 nm. A Cu wiring material comprising a first film formed on a substrate, a second film formed on the first film, and a third film formed on the second film. There,
The first film is a Ti-based barrier film, and is a film made of only Ti or a Ti compound,
The second film is a composite film of Ti and Cu, and the composition ratio of Ti or Ti compound and Cu or Cu alloy is between the interface in contact with the first film and the film surface. The composition ratio of Ti or Ti compound gradually decreases from 1 to 0 and the composition ratio of Cu or Cu alloy gradually increases from 0 to 1 between the interface contacting the first film and the film surface. Is a film that
The third film is a Cu-based film, and is a film made only of Cu or a Cu alloy.
Cu-based wiring material characterized by this.   A Ti-based barrier film, a Ti-based film, and a Cu-based film formed by heat-treating the Cu-based wiring material precursor according to any one of claims 1 to 4 between the base material and the Cu-based film. A Cu-based wiring material characterized by having a composite film with the system. A first film by a method of forming a film using a Cu or Cu alloy target and a Ti or Ti compound target using a PVD apparatus capable of simultaneously controlling and sputtering a plurality of targets; A method for forming a Cu-based wiring material precursor comprising a second film and a third film,
Using Ti or Ti compound target, as the first film, a step of laminating only Ti or Ti compound on the substrate,
Stacking the second film on the first film using a Cu or Cu alloy target and a Ti or Ti compound target;
A step of laminating only Cu or Cu alloy on the second film as the third film using a Cu or Cu alloy target;
Have
In the step of laminating the second film, a Ti or Ti compound target and a Cu or Cu alloy target are simultaneously ignited, and sputtering power applied to the Ti or Ti compound target is applied to the first film. The power value at the time of formation is gradually reduced to 0, and the sputtering power applied to the Cu or Cu alloy target is gradually increased from 0 to the power at the time of forming the third film, thereby the second film. A method for forming a Cu-based wiring material precursor, characterized in that: A first film by a method of forming a film using a Cu or Cu alloy target and a Ti or Ti compound target using a PVD apparatus capable of simultaneously controlling and sputtering a plurality of targets; A method for forming a Cu-based wiring material precursor comprising a second film and a third film,
Using Ti or Ti compound target, as the first film, a step of laminating only Ti or Ti compound on the substrate,
Stacking the second film on the first film using a Cu or Cu alloy target and a Ti or Ti compound target;
A step of laminating only Cu or Cu alloy on the second film as the third film using a Cu or Cu alloy target;
Have
In the step of laminating the second film, n is a positive integer, and Ti or Ti compound target and Cu or Cu alloy target are alternately used to laminate 2n layers, and k is 1 to n As an integer
The 2k-1st layer of Ti or Ti compound from the first film side gradually shortens the firing interval of the Ti or Ti compound target. When k is 1, k is the maximum and k approaches n So that it converges to zero,
The 2 kth layer of Cu or Cu alloy from the first film side gradually expands the firing interval of the Cu or Cu alloy target, and is maximum when k is n, and becomes 0 as k approaches 1. A method for forming a Cu-based wiring material precursor, which is formed so as to converge.   The method for forming a Cu-based wiring material precursor according to claim 7 or 8, wherein the first film has a thickness of 1 nm to 10 nm.   The method for forming a Cu-based wiring material precursor according to any one of claims 7 to 9, wherein the thickness of the second film is 10 nm to 50 nm.   A Cu or Cu alloy wiring material precursor formed by the method for forming a Cu wiring material precursor according to any one of claims 7 to 10 is heat-treated, and Ti is formed between the substrate and the Cu film. A method for forming a Cu-based wiring material, comprising forming a Cu or Cu alloy wiring material having a base barrier film.   The method for forming a Cu-based wiring material according to claim 11, wherein the heat treatment temperature is 450 ° C. or lower.

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